United States: The Western Mountains and Great Basin

West of the Great Plains are the lofty Rocky Mountains. This geologically young and complex system extends into NW United States from Canada and runs S into New Mexico. There are numerous high peaks in the Rockies; the highest is Mt. Elbert (14,433 ft/4,399 m). The Rocky Mts. are divided into four sections—the Northern Rockies, the Middle Rockies, the Wyoming (Great Divide) Basin, and the Southern Rockies. Along the crest of the Rockies is the Continental Divide, separating Atlantic-bound drainage from that heading for the Pacific Ocean.

Between the Rocky Mts. and the ranges to the west is the Intermontane Region, an arid expanse of plateaus, basins, and ranges. The Columbia Plateau, in the north of the region, was formed by volcanic lava and is drained by the Columbia River and its tributary the Snake River, both of which have cut deep canyons into the plateau. The enormous Colorado Plateau, an area of sedimentary rock, is drained by the Colorado River and its tributaries; there the Colorado River has entrenched itself to form the Grand Canyon, one of the world's most impressive scenic wonders. West of the plateaus is the Basin and Range province, an area of extensive semidesert.

The lowest point in North America, in Death Valley (282 ft/86 m below sea level), is there. The largest basin in the region is the Great Basin, an area of interior drainage (the Humboldt River is the largest stream) and of numerous salt lakes, including the Great Salt Lake. Between the Intermontane Region and the Pacific Ocean is the Pacific Mountain System, a series of ranges generally paralleling the coast, formed by faulting and volcanism. The Cascade Range, with its numerous volcanic peaks extends S from SW Canada into N California, and from there is continued south by the Sierra Nevada, a great fault block. Mt. Whitney (14,495 ft/4,418 m), in the Sierra Nevada, is the highest peak in the conterminous United States.

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• Related Articles
• The George W. Bush Presidency, 9/11, and Iraq
• Bush, Clinton, and Bush
• The Reagan Years
• Internationalism and the End of the Cold WarFord and Carter
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• The Great Society, the Vietnam War, and Watergate and the Vietnam War
• The United States in a Divided World
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• Expansionists and Progressives
• The Late Nineteenth Century
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• Colonial America
• European Exploration and Settlement
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• Religion and Education
• People
• Climate
• Major Rivers and Lakes
• The Pacific Coast, Alaska, and Hawaii
• The Western Mountains and Great Basin
• The Plains and Highlands of the Interior
• The East and the Gulf Coast
• Physical Geography
• Political Geography
• Geographical Studies

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